“We would be quite open to a discussion about a process that would lead to a negotiation for the thing, whatever it turns out to be, that follows 2020, and we are also fully willing to recognize that that might be a legal agreement.”

So here we are again, at the height of humanity’s annual cycle of talking about our response to the escalating climate crisis. This time around the stakes are higher than ever: the crisis has never been more pressing, yet the procrastination has never been more blatant.

I am, of course, referring to the 17th Conference of Parties (COP17) to the United Nations Framework Convention on Climate Change (UNFCCC) in Durban, South Africa, where world leaders are currently gathered. I use the term “leaders” to refer to the people who are in charge, rather than to imply they are demonstrating any actual leadership. On the contrary, by all indications the conference is heading for a catastrophic failure of leadership.

The only real leadership in Durban has been the protests from the reasonable voices who are being ignored: a broad coalition of the poorest countries (African and small island states), young people, the Occupy movement, and environmental groups. Collectively they form the “climate justice movement”.

They argue, fairly convincingly, that the talks are dominated by rich countries, in turn controlled by polluting corporations, who are attempting to dismantle the Kyoto Protocol and replace it with an even weaker voluntary regime. While Kyoto is weak, is riddled with loopholes, and has so far failed – global emissions have risen by half since the reference year of 1990, and by a record-breaking 6% in 2010 – it remains the only existing international treaty with a framework for legally binding emissions targets. And rich countries want to carry over from Kyoto the offsets and other loopholes which have made it ineffective.

At the 1992 Earth Summit in Rio de Janeiro, 154 nations signed the UNFCCC, with the objective of preventing “dangerous anthropogenic interference with the climate system” (there are now 194 parties). The parties have met annually since 1995, leading to the Kyoto Protocol in 1997. In Kyoto it was agreed that rich countries would cut their emissions by 5% relative to 1990 by 2008-2012, but the treaty became riddled with loopholes allowing creative accounting and offsets.

Since Kyoto came into force in Montreal in 2005, the negotiations are supposed to have been about a second commitment period of Kyoto after it expires next year. But while poor countries wanted a new treaty to complement Kyoto, rich countries wanted to replace it. In 2007, the Bali Roadmap called for an agreement by 2009. Instead we got the Copenhagen Accord, which poor countries allege was undemocratically agreed by a handful of rich countries who then bullied them into signing up at Cancun in 2010. The stated objective of the Cancun Agreements is to “hold the increase in global average temperature below 2°C above pre-industrial levels”.

Yet now in Durban, many rich countries are now refusing to sign up to Kyoto or any other treaty, instead advocating a “pledge-and-review” approach in which each country voluntarily pursues the emissions targets they put on the table at Copenhagen – targets far too weak to achieve the internationally agreed goal of preventing dangerous global warming – and delay discussion of the necessary scale of action until some later date.

In a pledge-and-review world, international climate negotiations are likely to bypass the UN process. Countries like Australia are seeking to establish bilateral emissions trading agreements between major emitters. At first sight bilateral negotiations might seem more promising than the UN consensus approach, where one stick-in-the-mud like the US can ruin the outcome for everyone. But in UNFCCC at least poor countries have a voice; bilateral agreements would mean even greater control by corporate and national interests.

Bilateral negotiations would be focused not on targets but on emissions trading. The climate justice movement sees carbon markets and offsets as scams to cover the lack of action by rich countries and shift the burden to poor countries (I am inclined to agree). Australia, for better or worse, is set to have an emissions trading scheme from 2015, and our Climate Change Minister Greg Combet says the Government’s most important priority in Durban is to discuss linking our emissions trading scheme with others. The Australian delegation is certainly not representing my views as an Australian.

The most concerning thing about pledge-and-review is the timescale for the “review” part. All except the poorest, most vulnerable countries, who have little clout in the negotiations, are completely ignoring the urgency of radical action. Many rich countries are seriously threatening to delay any global agreement until 2020, or they propose yet another “Roadmap” to negotiate a new treaty to take effect in 2020. The US delegation has gone so far as to say nobody will even consider increasing the ambition of their targets before 2020.

What planet are these people on?

Given how utterly useless the “political reality” is, there no justification for toning down my message. So here then is the truth.

The national pledges currently on the table would lead to not 2°C but 4°C global warming by 2100. Some countries, including Australia, have made further pledges that are conditional on international action; even if these are included global warming would still be 3°C by 2100. Note that these numbers are median values; the worst-case outcomes are considerably higher. 3°C or 4°C would also surely lead to greater warming from slow feedbacks.

4°C would be a global catastrophe. It is difficult to imagine how humanity could adapt. There is no precedent in human history: global temperature has varied by only a few tenths of a degree in the relatively stable climate of the last 10,000 years in which human civilization developed. When the Earth was 5°C cooler 20,000 years ago, New York was covered by an ice sheet. The last time global temperature was a few degrees warmer was 35 million years ago, around the time our ancestors split off from monkeys; there were no ice sheets at the poles and sea level was over 60 metres higher.

A 4°C future is not acceptable. The scale of action that is truly required can be summed up in two possible pathways, which I will call the Tripwire Pathway and the Safe Climate Pathway. Under the Cancun Agreements the world’s governments have agreed to achieve at least the Tripwire Pathway. However, many scientists, poor nations, and activists (including I) advocate the even stricter Safe Climate Pathway.

Tripwire Pathway: The objective is that of the Cancun Agreements: “hold the increase in global average temperature below 2°C above pre-industrial levels”. 2°C was previously known as the “guardrail” beyond which warming could become dangerous; now climatologists realise 2°C is quite dangerous in itself and is better described as a “tripwire” beyond which the climate could spiral out of control. To limit global warming by 2100 to 2°C, humanity must not exceed a certain budget of cumulative global emissions between 2010 and 2050. The budget for the Tripwire Pathway runs out in about two decades, meaning the world has four decades to get to near-zero emissions. To stay within the budget, global emissions must peak within the next decade (dubbed the “Critical Decade” by the Australian Government’s Climate Commission). If the peak in global emissions is delayed until 2020, then everybody will have until 2040 to get to zero emissions. If we choose the Tripwire Pathway, we risk some unmanageable impacts including the demise of small island states, and warming exceeding 2°C from slow feedbacks over centuries and millennia.

Safe Climate Pathway: The objective is to be sure of preserving a safe climate and preventing “dangerous anthropogenic interference with the climate system”. To avoid slow feedbacks that could lead to dangerous warming, humanity must return the Earth to energy balance, which means reducing atmospheric CO2 to ~350 ppm. Because of the long lifetime of CO2 in the atmosphere, to reduce its concentration humanity must stop emitting the gas so the oceans and vegetation can start absorbing it. In practical terms, everybody needs to cut fossil fuel emissions to zero or near-zero as soon as possible. A return to 350 ppm could be achieved by global fossil fuel emissions reductions of 6%/year beginning in 2013, followed by a large reforestation effort later this century. So on the Safe Climate Pathway the world has only about two decades to phase out fossil fuels. There is very little time to shift away from business-as-usual: every year the world delays, CO2 rises by another 2 ppm and the 350 goal slips further from our grasp. If we choose the Safe Climate Pathway, the peak in global temperature should be not much more than 1°C above pre-industrial temperatures.

The very immediate urgency of the problem has never been clearer. The extent of climate impacts centuries and millennia from now will be determined by policy decisions taken in the near future. On either of the above pathways global emissions need to peak and begin declining very fast very soon, preferably yesterday. Note that the emissions reduction rates mentioned above are global; the cuts in developed nations would need to occur even faster. At some point the required cuts become so steep they are practically impossible.

So here’s what I think should happen in Durban. The delegates should agree to aim for 350 ppm. All developed countries and emerging major emitters should make binding commitments which add up to the global target. There should be no international carbon trading or offsets; in particular land carbon measures should not be offsets for fossil fuel emissions. And there must be progress on a Green Climate Fund and technology transfer to help developing countries in mitigation and adaptation.

Voluntary pledge-and-review and bilateral agreements will not work. In the absence of a global agreement, most countries will continue to cite the inaction of others as cover for their own. A Roadmap to a treaty might sound good with a nice capital R, but after two decades of negotiations you’d think the world’s leaders could come up with an actual treaty that would solve the problem. There must be a legally binding framework for emissions targets; that framework could be a second commitment period of Kyoto.

Sound radical?

“We’re not radical. Radicals work for oil companies. The CEO of Exxon gets up every morning and goes to work changing the chemical composition of the atmosphere. No one has ever done anything as radical as that, not in all of human history.”